The man in the desire for more efficient agriculture, constantly seeks to develop pesticide products without
regarding that indiscriminate use causes pest adaptations, making them more resistant. In Chubut River Valley
(VIRCH), province of Chubut, Argentina, farmers use organophosphate herbicides such as glyphosate
(isopropylamine salt of N-phosphonomethyl glycine) for weed control in various crops, assuming the risk that
leaks involve on health and hygiene quality of its waters. Since microalgae quickly respond to environmental
changes due to their short generation times and their role as primary producers in aquatic ecosystems, they are
used in 72-96 h tests to provide information on some pollutants ecological effects. In this study, the sensitivity
of Chlamydomonas sp to glyphosate was evaluated comparing the inhibition percentages to a control, using
standard methodologies for the assessment of the essays. It was found that the EC50 was 68,57 mg/L, the
NOEC was 40,0 mg/L a.....